Dental research has had remarkable success in dental caries prevention. Specifically, it has been found that roughly fifty percent of children ages six through seventeen living in the United States are caries free. This remarkable progress during the last twenty years is due, in part, to better oral hygiene, use of fluoridated water, and fluoridated products, i.e., dentifrices.
Nevertheless, there are patients who remain susceptible to dental caries. For instance, twenty percent of all children account for roughly sixty percent of all carious lesions. Also, certain subjects with diminished salivary functions are especially prone to caries, because they produce limited amounts of saliva. Other risk factors, such as poor oral hygiene, physical or mental handicaps, and certain systemic diseases or disorders may also predispose individuals to dental caries.
Recent studies have demonstrated that elevated concentrations of fluoride in the mouth for extended periods will help reduce caries. A source of such fluoride is contained in controlled-release fluoride tablets which have been called intra-oral fluoride releasing devices (IFRD's). These IFRD's release fluoride into the oral cavity for extended periods up to six months to enhance prevention of dental caries.
Previous attempts to retain IFRD's in the mouth have failed for a variety of reasons. For instance, IFRD's produced by Southern Research Institute were designed to be bonded directly to the teeth. These IFRD's were found susceptible to debonding from masticatory forces or were subject to excessive wear caused by abrasives contained in toothpastes. What is desirable, therefore, is a system whereby IFRD tablets can be safely secured and retained in the mouth until their fluoride supply is exhausted.
In addition, it is desirable to have a system (an intra-oral fluoride release system or IFRS) whereby the tablets can be replaced periodically following depletion of their fluoride content. It is further desirable for these systems to be broadly useful for children undergoing active orthodontic treatment. In general these children have an increased risk to caries development because they are not able to adequately brush their teeth.
It is also desirable to provide an IFRS which does not cause severe irritation to mouth tissues. What is meant by severe irritation is ulceration or acute inflammation which interferes with oral function and nutrition, such as pain, induration or necrosis or purulent exudate from tissue in the vicinity of the IFRS.